Problem: What is the greatest common factor of $50$ and $45$ ? Another way to say this is: $\operatorname{gcf}(50, 45) = {?}$
The greatest common factor is the largest number that is a factor of both $50$ and $45$ The factors of $50$ are $1$ $2$ $5$ $10$ $25$ , and $50$ The factors of $45$ are $1$ $3$ $5$ $9$ $15$ , and $45$ Thus, the greatest common factor of $50$ and $45$ is $5$. $\operatorname{gcf}(50, 45) = 5$